The present invention relates to computer animation. More particularly, the present invention relates to techniques and apparatus for efficient rendering of related image frames.
Throughout the years, movie makers have often tried to tell stories involving make-believe creatures, far away places, and fantastic things. To do so, they have often relied on animation techniques to bring the make-believe to “life.” Two of the major paths in animation have traditionally included, drawing-based animation techniques and physical animation techniques.
Drawing-based animation techniques were refined in the twentieth century, by movie makers such as Walt Disney and used in movies such as “Snow White and the Seven Dwarfs” (1937) and “Fantasia” (1940). This animation technique typically required artists to hand-draw (or paint) animated images onto a transparent media or cels. After painting, each cel would then be captured or recorded onto film as one or more frames in a movie.
Physical-based animation techniques typically required the construction of miniature sets, props, and characters. The filmmakers would construct the sets, add props, and position the miniature characters in a pose. After the animator was happy with how everything was arranged, one or more frames of film would be taken of that specific arrangement. Physical animation techniques were developed by movie makers such as Willis O'Brien for movies such as “King Kong” (1933). Subsequently, these techniques were refined by animators such as Ray Harryhausen for movies including “Mighty Joe Young” (1948) and Clash Of The Titans (1981).
With the wide-spread availability of computers in the later part of the twentieth century, animators began to rely upon computers to assist in the animation process. This included using computers to facilitate drawing-based animation, for example, by painting images, by generating in-between images (“tweening”), and the like. This also included using computers to augment physical animation techniques. For example, physical models could be represented by virtual models in computer memory, and manipulated.
One of the pioneering companies in the computer aided animation (CA) industry was Pixar. Pixar developed both computing platforms specially designed for computer animation and animation software now known as RenderMan®. RenderMang® was particularly well received in the animation industry and recognized with two Academy Awards®.
The named inventor of the present invention co-developed the original RenderMang® software. During this time, he made several engineering assumptions which affected the operation of the software. One assumption was that a geometric description of scene stored in memory was relatively small. The geometric scene description typically included the geometric description of a location, objects, object placements, and the like. The named inventor also assumed that the resolution of the output image frame was large and could not be economically stored in computer program memory.
In light of these assumptions, when it came time to render a frame, the geometric scene data would first be moved from disk memory to program memory. The frame would then be subdivided into a series of smaller frame portions, termed buckets, and portions of any object appearing in a bucket, would then be rendered. This process would then be repeated for the remaining buckets in the frame, until the frame was rendered. The process would thus render all objects in one frame, before beginning the next frame. In some respects, the animation process of RenderMan® was similar to the traditional animation techniques, mentioned above, in that one frame would be rendered at a time. Although parallel processing techniques were available and implemented, each frame would still be individually and separately rendered distinctly from other frames.
In light of the above, the inventors of the present invention have realized that it is desirable to make further enhancements in the area of animation software to facilitate the process of making animated features.